Mixed trisiloxanes



United States Patent 3,122,579 MIXED TRISFLOXANES Robert H. Leitheiser, Midland, Mich, assignor to Dow Corning Corporation, Midland, Mich, a corporation of Michigan No Drawing. Filed Oct. 17, 1960, er. No. 62,825 3 Claims. (Ci. 269-4483) This invention relates to hydrolyzable trisiloxanes and to trisiloxanediols containing at least two kinds of siloxane units.

One of the most important advances in the last two decades in the art of elastomeric materials has been the development of organopolysiloxane rubbers. One of the best ways of preparing organopolysiloxane rubber gums is by the polymerization of the corresponding cyclotrisiloxanes. The present invention relates to intermediates for use in the preparation of mixed cyclotrisiloxanes. The materials of this invention open up new possibilities in the preparation of siloxanes containing more than one kind of siloxane unit because mixed cyclotrisiloxanes otter a convenient way of introducing various kinds of siioxane units into siloxane rubber polymers. Since most commercial siloxane rubber polymers are copolymers containing at least two different kinds of siloxane units, the compositions of this invention contribute substantially to the art of silicone rubber manufacture.

It is the object of this invention to prepare novel compositions of matter which are useful in the preparation of cyclicorganopolysiloxanes as specifically disclosed and claimed in applicants copendiug application entitled A Method of Making Cyclotrisiloxanes, Serial Number 62,895, filed October 17, 1961, now abandoned. Another object is to prepare novel trisiloxanediols and trisiloxane methoxides which can be polymerized via hydroxyl condensation or hydroxylmethoxy condensation to produce organopolysiloxane gums. Other objects and advantages will be apparent in the following description.

This invention relates to linear organosiloxanes of the formula R2 R5 R2 XSiOSiOSiX in which X is of the group chlorine, acetoxy, methoxy, and hydroxyl and R is selected from the group consisting of monovalent hydrocarbon radicals and monovalent halohydrocarbon radicals, in which siloxane the R group attached to at least one of the silicon atoms is diiferent from the other R groups.

As can be seen, the above definition requires that there be at least two difierent kinds of siloxane units in the trisiloxane. There can, of course, be three different kinds of siloxane units. It can also be seen that all of the R groups, except one, can be the same. On the other hand, all of the R groups can be different. Examples of typical variations are illustrated specifically by the compounds 'Me Et ClSiOSi OSiCl Pl] Vi M02 Phg Eta (315i OSl Osl C1 3,122,579 Patented Feb. 25, 1964 For the purpose of this invention R can be any monovalent hydrocarbon radical, such as alkyl radicals such as methyl, ethyl, isopropyl, octadecyl or myricyl; any unsaturated aliphatic hydrocarbon radical such as vinyl, allyl, hexenyl or propargyl; any cycloaliphatic hydrocarbon radical such as, cyclohexenyl, cyclopentyl, cyclohexyl and methylcyclohexyl; any aromatic hydrocarbon radical such as phenyl, xenyl, naphthyl, tolyl or xylyl, and any aralkyl hydrocarbon radical such as benzyl, fiphenylethyl, and gamma-phenylpropyl. R can also be any monovalent halohydrocarbon radical such as chloromethyl, trifluoropropyl, C P CH CH chlorophenyl, bromoxenyl, u,a,a-trifluorotolyl, chlorobenzyl, trifiuorovinyl, chlorocyclohexyl and tetrachlorophenyl.

The compositions of this invention in which X is chlorine or acetoxy are best prepared by reacting 2 mols of a silane of the formula R SiX with one mol of a silane diol of the formula R Si(OH) This reaction is best carried out in the presence of an acid acceptor, such as pyridine, ct-picoline, tributylamine, di-n-hexylamine or cyclohexylamine.

The acid acceptor should be present in slight molar excess over that required to react with all of the HCl or acetic acid formed during the reaction. The reaction is represented by the equation The variations in the structure of the trisiloxaue are brought about by employing silanes and silane diols having different groups substituted on the silicon. if one wishes to prepare a siloxane having two types of siloxane units, then one reacts a silane with a silane diol having substituent R groups, differing from those of the silane. -In those cases where one wishes to prepare a trisiloxane having 3 types of siloxane units, then one reacts a mixture of 2 silanes having different R groups on the silicon with a silane diol having R groups difiering from either of the silanes. For example, one can react a mixture of one mol of dimethyldichlorosilane and one mol of phenylmethyldichlorosilane with one mol of diphenylsilane diol to produce the compound ME: Ph: Ph ClSi OSi OSiCl The reaction of the chloro or acetoxy silane with the silane diol is best carried out in the presence of an inert solvent i.e., one which will not react with the chloro or acetoxy silane, such as hydrocarbons such as toluene, petroleum ether and xylene; others such as the dimethyl ether of ethylene glycol, n-butyl ether or diethyl ether; ketones such as acetone or dibutylketone and chlorinated hydrocarbons such as methylenechloride, chlorobenzene or chloroform.

The trisiloxanes in which X is methoxy are prepared by reacting silanes of the formula R2 ClSiOMe with the silane diols R Si(OH) in contact with an acid acceptor such as pyridine or other amines. The reaction is best carried out at from 0 to 30 C.

Methoxychlorosilanes can be prepared by mixing one mol of Me SiCl with one mol of Me Si(OMe) and allowing the mixture to equilibrate. The equilibration goes at room temperature or above.

The siloxane diols of this invention are best prepared by the careful hydrolysis of the corresponding chloro or acetoxy siloxanes. This hydrolysis is best carried out by a adding the chloro or acetoxy siloxane to water containing an acid acceptor such as sodium bicarbonate. The hydrolysis should be carried out under mild temperatures i.e., about room temperature and the trisiloxane diol can EXAMPLE 2 Employing the procedure of Example 1, the following silanes were reacted with the following silane diols he purified by crystallization. to give the trisiloxanes shown in the table below:

Table I Acetoxy Silano Silano Diol Trisiloxane .P.,

C./mrn.

BIC: Pl); RIP/2 Me s1(000MQ) Ph suorm McCOOSi ()Si OSiOOCMo 100/2 Me Me Meg l\ Ie Sl(OOCMc)z MeViSi(OH) MeCOOSi os losioocMe 160/68 i P Pi]; Ph1Si(OOGMIe) PhMoSi(OH) MeOOOSi O\iIOSiOOCMe 300/2 The chlorosilanes employed in the invention are well EXAMPLE 3 known commercial materials. The diacetoxysilanes employed as starting materials can be prepared by reacting A mixture of 2 mols of dimethyldichlorosilane and 95 the corresponding dichlorosilanes with acetic anhydride. gof -p f in about 509 0f dlethylethef was 19 The silane dials employed her in e, be t prepared by in a container and cooled in an ice bath as a solution of adding the corresponding chlorosilanes to a stoichiometric K101 0f p lf y h 111 a mlXtufe Of 500 amount of water in diethylether in the presence of aniof father and 93 gof 3111111? was added Slowly Over a line or other amine acid acceptors. This reaction should pfiflgd 0f 2 hOllrS- The mlXiUre as rr d f r a f w be carried out at or about 0 C, The ol ti i h minutes longer and then filtered and the ether was refiltered to remove the amine hydrochloride and the reloved from the fi Product was distilled t0 suiting filtrate can be used directly to prepare the trig a 69pefcentylfildofthe315110145136 siloxanes of this invention. N M M In this specification the following abbreviations are i C1 employed, Me for methyl, Et for ethyl, V1 for v1nyl and Ph Ph for phenyl. O

The following examples are illustrative only and should boiling at 123 at 10 not be construed as limiting the invention which is properly delineated in the appended claims. E MPLE 4 EXA MPLF 1 Employing the procedure of Example 3, the following chlorosilanes were reacted with the following silane diols A mixture of 476 g. of phenylmethyldiacetoxysilane in to produce the following trisiloxanes:

Table II Chlorosilane Silane Diol Trisiloxane .P.

C./mm

P11 Mcz Ph PhgSiClz I\Lte Si(OH)g ClSi OSi OSiOl l- 228/1 Meg Ph M02 Me siol PhViSKOH); O1si os iosim 102/20 IVIGZ NIB leg Mezsiclg MeEtSKOH); ClSi 0%105101 105/30 Me Me Meg Me Me; lUO SiClz PhOHCH SKOHh 01st OSCifiHiCl 128/2 CHllIe P11 Me Me; Me Me: MezSiOh CF CH CH SKOII); OlSi OgilgsiOl 105/19 011i OFs about 200 cc. of diethylether was placed in a container EXAMPLE 5 Ph P112 Ph MeCOOSi 0S1 OSiOOCMe Me Me boiling at 245 C. at 2 mm.

An ether solution of the trisiloxane M02 P11 Meg MeCOOSi OSi OSi OOOMe was added slowly with stirring to an ice water solution of sodium carbonate. After one hour of agitation the ether solution was washed with water and with sodium carbonate solution until it was neutral. The product was dried over an anhydrous sodium carbonate. The

ether was allowed to evaporate giving a crystalline prodnet. The first crop was removed by filtration and the evaporation was continued giving a second crop of crystals. These were the compound Meg P11, Me; 5 HOSi osi OSi OH melting at 114 to 117 C.

EXAMPLE 6 When the following acetoxy trisiloxanes were hydrolyzed in accordance with the method of Example 5, the following diols were obtained:

Table III Melting Acetoxysilane Diol P oint,

Phi Ph Ph; P11 Ph Ph MeCOOSiOSiOSiOOCMe HOSiOSiGSiOH 92-94 Me Me Ph Ph; Ph Ph Ph Ph MeOOOSiOSi OSiOOCMe HOSiOSi OSiOH Liquid Me Me Me Me EXAMPLE 7 59 g. of

P112 Meg Pl]: ClSi OSi OSi G1 was dissolved in 200 cc. of acetone and the solution was slowly added to a mixture of ice and Water containing 26 g. of sodium carbonate. The mixture Was stirred for minutes and toluene was added. The toluene layer was washed twice with water, then separated and dried over sodium sulfate. The product crystallized and toluene was added to make a slurry which was filtered. The solid product was Washed 3 times with toluene and was found to be the diol Phg Men Phg HOSi OSi OSi OH melting 102 to 103 C.

EXAMPLE 9 When the following chlorosiloxanes are hydrolyzed in accordance with the procedure of Example 7, the following trisiloxane diols are obtained:

Table IV Chlorosiloxane Diol Meg P11 M92 M82 Pb Me; 018i OSiOSiCl HOSi OSiOSiOH Me Me Meg Ph Me: Me: P11 M62 GISi OSiOSiGl HOSi OSiOSiOH Vi Vi M62 Me Me: Me; Me Me: 018i 081 OSiOI HOSi OSi OSiOH Et Et Me; Me Me: Me: Me Me, CISi OSi OSiOl HOSi OSi OSiOH CH2 CH2 OHMe OHMe Ph Ph M92 Me Me; Me; Me Me; 0181 OSi OSiCl HOSi OSi OSiOH CH2 CH2 OH, OH; CF14 GFQ Me Me Me Me Me Me 015i 081 OSiCl HOSi OSi OSiOH CH3 CH2 CH2 H2 0 O O C III s II] HI [1] OH OH OH OH Me; Me M82 Mez Me Me; ClSi OSi OSiOl HOSi OSi OSiOH M62 Me Meg Me: Me Mei OlSi OSi OSiGl HOSi OSi OSiOH EXAMPLE 10 1 mol of dimethylmonochloromethoxysilane was dissolved in 250 cc. of ether and cooled in an ice bath. 0.5 mol of diphenylsilanediol was dissolved in one mol of a-picoline and one liter of diethyl ether. The solution of the diol was added with agitation to the cold solution of the dimethylchloromethoxysilane. The mixture was stirred for 30 minutes, filtered and stripped at 100 C.

The product was distilled at reduced pressure to give the compound Me Phz Me MeOSi OSi OSi That which is claimed is: 1. A composition of the formula P11 M92 P11 XSi 0st OSi X in which X is selected from the group consisting of chlorine atoms and hydroxyl radicals.

2. A trisiloxane of the formula P113 M83 P113 0181 OSi OSi G1 3. A composition of the formula P11: Me: P11: HOS; OSi osi 0H References Cited in the file of this patent UNITED STATES PATENTS 2,902,507 Hyde et al. Sept. 1, 1959 2,911,427 Brown Nov. 3, 1959 2,915,544 Holbrook et al. Dec. 1, 1959 FOREIGN PATENTS 816,535 Great Britain July 15, 1959 OTHER REFERENCES Daudt et al.: Jour. Am. Chem. 800., volume 74 (1952), pages 386-90.

Sokolov et al.: Izvest. Akad. Nauk. SSSR, Otdel Khim. Nauk (1957), pages 806-1l (Chem. Abstracts 3, 668).

Sokolov: Zhurnal Obshchei Khim., volume 29 (January 1959), pages 253-63. 

1. A COMPOSITION OF THE FORMULA 